The present disclosure relates to an optical waveguide circuit device.
Known optical switches that are used in optical communication include optical waveguide circuit devices including a Planar Lightwave Circuit (PLC) made of silica-based glass. There is a disclosed technology in which, for optical waveguides constituting the PLC, zirconia (ZrO2) is used as a dopant for increasing the refractive index (see JP 2013-210623 A). ZrO2 is a material having a high refractive index and a low coefficient of thermal expansion, as compared with germania (GeO2). The use of ZrO2 as a dopant makes it possible to achieve a significantly increased relative refractive index difference Δ of the core (optical waveguides) to the cladding layer, as compared with PLCs in which GeO2 is used as a dopant. Consequently, the minimum bend radius allowable for the optical waveguides is reduced, and thus a miniaturization, cost reduction, and dense integration of PLCs can be expected. Hence, ZrO2 is expected to serve as a material capable of achieving miniaturized PLCs and optical waveguide circuit devices using a PLC and also reduced stress remaining in the optical waveguides.